Combination automobile instrument panel and horn loudspeaker



J. H. GUYTON ETAL 3,276,538 COMBINATION AUTOMOBILE INSTRUMENT PANEL AND HORN LOUDSPEAKER 2 Sheets-Sheet l 6 6, 5 9 l 1 m 4 J d t e C l O i F ATTORNEY Oct. 4, 1966 J H. GUYTON ETAL 3,275,538

COMBINAION AUTOMOBILE INSTRUMENT PANEL AND HORN LOUDSPEAKER Filed Jan. 13, 1955 2 Sheets-Sheet 2 INVENTORS 14T TORNEY United States Patent O 3,276,538 COMBINATION AUTGMOBILE INSTRUMENT PANEL AND HORN LOUDSPEAKER James II. Guyton and Donald E. Brinkerhoff, Kokomo,

Ind., assignors to General Motors Corporation, Detroit,

Mich., a corporation of Delaware Filed Jan. 13, 1965, Ser. No. 425,218 2 Claims. (Cl. 181-31) This invention relates to electro-acoustic transducer means and more particularly to means for converting electrical oscillations into sound waves more effectively in automotive vehicles.

At the present time the electrical output from an automotive radio receiver is conventionally fed to `an elliptical speaker horizontally mounted in the center of the top of the instrument panel facing upwardly to d1scharge sound waves generated thereby against the inner face of the windshield. This only uses a portion of the windshield as a horn loading means Iand does not obtain la maximum effect.

It is an object in making this invention to provide 1mproved electro-acoustic transducer means for automotive vehicles.

It is a further object in making this invention to provide a combination instrument panel top and loudspeaker driven by the radio receiver.

It is `a still further object in making this invention to provide both high frequency and low frequency horn loads for the speaker of a radio receiver formed in part by portions of the vehicle body.

It is a still further object in making this invention to provide a matching horn load for a speaker for a radio receiver, said horn load being formed in part by portions of the vehicle body so that the size of the receiver required may be reduced to a minimum to save cost, space and power consumption.

With these and other objects in view which will become apparent as the specification proceeds, our invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawings, in which:

FIGURE 1 is a partial, perspective view of the inside of a vehicle showing the top of the instrument panel ernbodying our invention, the outline of the horn channel being shown in dashed lines;

FIG. 2 is a top plan View of the instrument panel assembly embodying our invention, parts being broken away and shown in section;

FIG. 3 is a sectional view taken on line 3 3 of FIG. 2 in the direction ofthe arrows;

FIG. 4 is a sectional view taken on line 4 4 of FIG. 2 in the direction of the arrows;

FIG. 5 is a top plan view of the driver .and throat assembly unit used to match the transducer to the horn proper, taken on the line 5-5 of FIG. 4;

FIG. 6 is a -partial perspective view of the driver unit, transducer and horn assembly, parts being broken away and shown in section;

FIG. 7 is a perspective view si-milar to FIG. 1 of a modied form of our invention utilizing both high and low frequency horn systems;

FIG. 8 is .atop plan view of the instrument panel shown in FIG. 7 with parts broken away and shown in section;

FIG. 9 is a top plan view of driver and throat assembly unit used in this modified form;

FIG. 10 is a sectional view taken on line 10-10 of FIG. 9 in the direction of the arrows; and,

FIG. 11 is a sectional View taken on the line 11-11 of FIG. 9 in the direction of the arrows.

It is, of course, a well known physical fact that the efficiency of the transducer of an electro-acoustic system ICC may be improved by using the same with a horn system to obtain a greater -audio output. Horn speaker combinations have been used where high volume sounds are required, such as for outdoor use. Such a combination also permits the reduction in size of the radio receiver feeding the transducer if, by such combination, more than sufficient sound output is obtained. In the a-utomotive vehicle, if horn means can be associated withthe transducer and/or loudspeaker to provide -considerably more volume of sound, then the radio receiver feeding the transducer can be reduced in size and power to save cost. The efficiency of a transducer is greatly increased by combining the same with an effective horn load in the frequency range above the horn low frequency cut off. The cut off frequency is determined by the flare rate of the horn. This increased efficiency results from lthe improved acoustic impedance match between the air and the transducer diaphragm provided by said horn. In the present instance the system consists of a transducer matching driving unit and a single large horn output or multiple horn outputs, the horn outputs being so designed as t-o fit into the automobile body enclosure and utilize a portion of the body to assist it in directing the output sound waves for final amplification.

Referring now more specifically to FIG. 1 of the drawings, there is shown therein the normal instrument panel 2 of an automotive vehicle 4 which ts across the front of the body above the steering wheel 6. In the present instance the instrument panel is considered to be made of such material that it can be cored out or provided with channeling as will be described more in detail as the description proceeds. The instrument panel proceeds across the front of the vehicle below the windshield 8. The instrument panel itself is intended to provide a large horn section for picking up sound waves from a matching driver section 10 (see FIG. 4) and discharging them through elongated slots 12 below the windshield, said slots being in the nature of defroster slots conventionally used. The driver unit 10 is adapted to support a small electro-acoustic transducer 14 which is driven by the output of a radio receiver 16 (FIG. 3). The intended object of the whole assembly is to receive sound waves created by the transducer 14 and conduct the same through an ever increasing sectional channel from the driver unit through the main horn unit and discharge the sound waves through the elongated slots 12 against the inside surface of the windshield and instrument panel top which extends the horn and directs the sound toward the occupants of the car. The total elongated horn channel may be of exponential shape or it may be substantially that or not depending upon the desires of the designer.

It will be noted that in the matching driver block 10 as specifically shown in FIGS. 5 and 6, the central opening 18 is that which receives the sound waves from the transducer 14. This central opening 18 is connected with a spiral channel 20 in the upper surface of the driver member 10 whichever increases in its cross-sectional area until it reaches .approximately one and 0ne-half turns and terminates at the locale 22. This locale is mounted directly under the inner end 24 of the built in horn section 26 which is roughly spiral, formed in the instrument panel board directly which expands until it matches the front of the panel board and may discharge through either of the slots 12. The panel itself may be made of any desired material in which the channel may be cut and which will be relatively vibration proof, such as foamed polyurethane which is a good damping material and is also used in some padded instrument panel tops `at the present. The sound track of the horn is coiled on top of the lower panel which projects underneath to enclose the operating channel. Defroster nozzles, if used, may be combined with the sound slots if desired.

Thus when the radio receiver 16 drives the transducer 14, sound is applied to the opening 18 and induced into the spiral expanding cavity 20 in the driver 10 and fed into the larger semi-spiral cavity 26 to be discharged through the slotsllZ againstthe inside slantingsurface of the windshield using substantially the 'whole Width of the latter as a sound chamber providing a high eiciency acoustic system for obtaining maximum sound output from a minimum amount of electrical input. Such a system also works excellently throughout the audio response range down to a very low frequency.

A second species of invention is illustrated in FIGS. 6 through 1l, inclusive. The principal difference between this structure and the earlier form already described is that it provides two separate channels from the transducer 14' to the listening area, one high frequency channel and one low frequency channel, each channel acting as a resonator for frequencies in its band, so that while both the high and the low frequencies originate in the saine diaphragm one band is resonated by and conducted through one channel and the other through the second channel. 'By providing two separate channels instead of one to handle all frequencies a more satisfactory overall response is obtained by the listener.

Referring now more specifically to the drawings, a modified driver section 10', FIGS. 9 and 10, is provided to which a double-ended transducer :unit 14 may Ibe applied. In this case the spiral channel discharges downwardly into a connecting tube rather than upwardly into the small end of the expanding channel 26.

As shown in FIG. 7 the instrument panel block 32 extends across below the windshield and is, .as before, so cored out as to provide a spiral expanding channel 26 which discharges through two upper forward slots 12 on opposite sides of the center below the windshield. The driver unit, however, is in this case mounted below the center of the windshield and the upper end of opening 1,8 from the top of the transducer 14 is connected directly to the small end of an expanding horn 34 terminating in a central elongated slot 36. The high frequencies are, therefore, provided with a direct path from the upper surface of the transducer diaphragm through the opening 18 and thence through the horn 34 to be discharged against the slanting inner face of the windshield and directed back into the interior of the body. The horn 34 projects directly through the center of the channel 26. The small spiral channel 20' in the driver 10 now is coupled to the lower surface of the transducer diaphragm 17 and the large end of channel 20 is connected through a coupling hose 30 over to the small end 24 of the channel 26 and the sound therefrom, as before, passes through the expanding channel 26 to be directed through slots 12 -against the inside slanting surface of the windshield and directed back as before mentioned. In this manner the two separate paths will more adequately provide proper matching channels between the transducer and the air.

In instances where a rear seat speaker is used, this same type of construction can be used on the back package shelf as well. It is used to replace the normal instrument cover. In this instance the package shelf is replaced by a foamed polyurethane pad having horn channels therein to develop the proper expanding horn path for the sound introduced from a rear speaker in the same manner as that developed above.

What is claimed is:

1. In a sound reproducing system for an automotive vehicle having a body with a windshield, an electroacoustic transducer, a at solid transverse instrument panel member extending across the body beneath the windshield with a spiral channel therein terminating in slots below the windshield, a mounting block having a spiral channel therein mounted on the 'bottom of the instrument panel member with the large end of its spiral channel connected with the small end of the channel in the instrument panel member to form a single elongated expanding channel, said transducer mounted on said block and -connected directly to the small end of the spiral channel therein to increase the eciency of conversion of electrical to acoustical energy produced thereby, and di` rect said energy into the interior of the vehicle.

2. In a sound reproducing system for an automotive vehicle having a body with a windshield, an electro-acoustic transducer having a diaphragm, a flat solid transverse instrument panel member extending across the body beneath the windshield with a spiral channel therein terminating in slots below the windshield, a mounting block having a central opening and a spiral channel therein mounted on the bottom of the instrument panel member, the small end of the spiral channel being connected to the central opening and with the large end of its spiral channel connected with the small end of the channel in the instru-ment panel member to form a single elongated expanding channel, said transducer being mounted in the central opening so that said small end of the spiral chamber is coupled to one side of the transducer diaphragm, an expanding horn member connected to the transducer and coupled to the other side of the transducer diaphragm mounted in said mounting "block, supported by said transverse instrument panel member and terminating at the upper face thereof between the slots in the member below the windshield, said transducer thus -being connected to the small ends of the two expanding horns so that the higher frequencies may be projected more effectively by the smaller expanding horn member and the lower frequencies by the larger spiral expanding horn in the instrument panel member.

References Cited by the Examiner UNITED STATES PATENTS 1,930,915 10/1933 Wente 181`27 2,058,132 10/1936 Cirelli l8l-27 2,975,852 3/1961 Chave ISI- 31.1 FOREIGN PATENTS 308,769 5/1930 Great Britain. 864,957 4/1961 Great Britain.

RICHARD B. WILKINSON, Primary Examiner. S. I. TOMSKY, Assistant Examiner. 

1. IN A SOUND REPRODUCING SYSTEM FOR AN AUTOMOTIVE VEHICLE HAVING A BODY WITH A WINDSHIELD, AN ELECTROACOUSTIC TRANSDUCES, A FLAT SOLID TRANSVERSE INSTRUMENT PANEL MEMBER EXTENDING ACROSS THE BODY BENEATH THE WINDSHIELD WITH A SPIRAL CHANNEL THEREIN TERMINATING IN SLOTS BELOW THE WINDSHIELD, A MOUNTING BLOCK HAVING A SPIRAL CHANNEL THEREIN MOUNTED ON THE BOTTOM OF THE INSTRUMENT PANEL MEMBER WITH THE LARGE END OF ITS SPIRAL CHANNEL CONNECTED WITH THE SMALL END OF THE CHANNEL IN THE INSTRUMENT PANEL MEMBER TO FORM A SINGLE ELONGATED EXPANDING CHANNEL, SAID TRANSDUCER MOUNTED ON SAID BLOCK AND CONNECTED DIRECTLY TO THE SMALL END OF THE SPIRAL 